▎ 摘　　要

It is very important to obtain large-scale and high-quality graphene for its application. However, the efficient preparation of large-scale and defect-free graphene is difficult by using a general method. In this report, a conjugated ionic liquid (IL) is designed and synthesized, which is used as a green medium to easily exfoliate graphite into graphene with the assistance of microwave irradiation. The as-prepared IL-functionized graphene nanoplatelets (GNP(IL)) is few-layer, large-size and defect-free, which is attributed to the strong pi-pi and cation-pi interactions between conjugated IL and graphene layers. And the results show that a relatively high yield of 40% is obtained. The high-quality GNP(IL) could be dispersed in organic solvent homogeneously and stably with a high content, which is beneficial for its further applications. Furthermore, this GNP(IL) is used to composite with polyetherimide (PEI) to improve the conductivity of polymer. As compared with pure PEI, a sharp decrease of 11 orders of magnitude in volume resistivity is obtained for PEI composite with only 0.75 wt% GNP(IL), which keeps a good mechanical property as well. (C) 2018 Elsevier Ltd. All rights reserved.